A polyphenylene ether resin can have good thermal stability and mechanical strength, and a product made using the same can have excellent dimensional stability when manufactured. However, because it is hard to manufacture the polyphenylene ether resin alone, polyphenylene ether resin can be blended with a polystyrene resin having good compatibility. The blend can then be used in the production of various products such as interior/exterior materials for electronic devices.
While the blend of polyphenylene ether resin and polystyrene resin has good processability, it can also have deteriorated impact strength. Degradation of impact strength can be prevented by using a rubber-reinforced polystyrene resin in the blend of polyphenylene ether resin and polystyrene resin. However, the resin composition should have flame retardancy when used to produce products such as electrical/electronic products or office machines, such as monitors and faxes, which generate heat in operation.
A known method for imparting good flame retardancy is to use a halogen compound and an antimony compound together. For example, acrylonitrile/butadiene/styrene (ABS) resin or polystyrene (HIPS) resin can be mixed with halogen compounds and antimony compounds at a ratio of 2.5 to 4:1 in order to impart flame retardancy.
However, if an antimony trioxide is used as the antimony compound, the colorability of the resin composition can deteriorate because antimony trioxide is a white inorganic material. Thus, it can be difficult to provide color to the product, particularly a deep black color. Also, if the antimony compound is used with the halogen compound, there can be problems such as discoloration and generation of gas at high injection molding temperatures because of the reaction between the antimony compound and the halogen compound.
If the halogen compound is used without the antimony compound, the same flame retardancy can be obtained if double or three times the amount of the halogen compound is used. However, in this case, mechanical properties, such as impact strength, tensile strength, flexural strength and the like, and thermal properties, such as heat resistance and heat deflection temperature, can be degraded.
In addition, when the halogen compound and the antimony compound are used together, it can be difficult to make a light weight product due to an increase in the specific gravity of the resin composition.
A bromine-based flame retardant and a non-halogen-based flame retardant can be used to improve the flame retardancy of a blend of rubber-reinforced polystyrene resin and polyphenylene ether resin. However, a large amount of polyphenylene ether resin is used to improve flame retardancy, which can degrade the fluidity (workability), and the generation of gas in use at a high temperature leads to degradation of thermal stability. To solve this problem, a fluidity enhancer can be necessary to improve fluidity, and a thermal stabilizer can also be necessary to improve the thermal stability.
Korean Patent Publication No. 2010-0073148 discloses a flame retardant thermoplastic resin composition using a base resin comprising rubber-reinforced polystyrene resin and polyphenylene oxide resin with a diphenyl ethane bromide mixture. However, in this case, fluidity can be deteriorated due to using a large amount of polyphenylene oxide and diphenyl ethane bromide mixture.